1. Field of the Invention
This invention relates to suspension systems for vehicles. In one of its aspects, the invention relates to trailing arm suspensions for mounting an axle to a vehicle frame wherein each trailing arm comprises a pair of arms pivotably mounted to a frame bracket at one end and pivotably mounted to an axle plate at another end.
2. State of the Prior Art
Air spring suspensions are currently used to suspend the axles of trailers or other commercial vehicles. A typical air suspension assembly includes a trailing arm pivotally mounted at one end to a vehicle frame through a frame bracket. An air spring is mounted between the frame and the other end of the trailing arm. An axle is usually mounted to the trailing arm in proximity to the air spring. Two suspension assemblies are typically associated with each axle.
A problem associated with prior art air spring suspensions occurs when the axle and an associated trailing arm are deflected due to loading or irregularities in the road surface as the vehicle travels. When deflected, one end of the trailing arm rotates about a pivot point on the frame bracket, which causes the distal end of the trailing arm to swing in an arc. Since the air spring and axle are typically mounted at the distal end, they also undergo arcuate movement. The arcuate movement of the lower part of the spring results in a fore and aft movement and angular rotation of the air spring lower portion. Consequently, typical air springs are designed with a height to compensate for both axle deflection, fore and aft, and rotational movement. The increased air spring height necessitates an increase in material and bladder length, which results in greater manufacturing expense.